This invention relates to apparatus for sampling particulate material, especially wood chips as they are being fed downwardly through a chute or the like.
Wood chips arrive at wood pulping facilities usually in carload lots. Due to the large quantities involved, and the manner of shipment, it has been found difficult to sample the chips with sufficient reliability to ensure adequate quality control. One manner of sampling has been the removal of a quantity of chips from the carload, prior to unloading. Another manner of sampling has been to intercept a quantity of chips as they pass through an unloading chute. Methods such as these have involved random, manual sampling, leading to unreliable analysis of the makeup of a chip lot.
Prior art apparatuses have been directed to automatic sampling of granular, or particulate materials in lots of different particle sizes but generally similar particle shapes. The following U.S. patents are representative of apparatuses for automatic sampling of the aforementioned types of materials:
U.S. Pat. No. 3,595,087 discloses apparatus for removing samples of granular material flowing through a horizontally extending conduit 2. The apparatus includes (FIG. 1.) a rotatable and reciprocable tube 6 extending with acute angularity through the conduit wall 14, and presented upstream as respects material flow. The end 8 of the tube 6 is cut on a bias, so that manual rotation of the tube between fixed positions controls the rate of material flow into end 8 of the sample tube 6, flow through the tube being controlled by a valve 32. Reciprocal positioning of the tube vertically compensates for variation in material density due to horizontal flow.
U.S. Pat. No. 3,138,950 discloses apparatus for sampling particulate material including (FIG. 2.) a rotatable probe 50 having an opening. The probe may be rotated between an open position with the opening facing upstream, in a horizontal transfer line 11 of a pneumatic transfer system, and a closed position with the opening facing downstream. The probe is rotated through gearing 51, 52, by motor 53.
U.S. Pat. Nos. 888,471 and 3,060,746 disclose additional examples of sampling apparatus having rotatable elements movable between opened and closed positions within streams of particulate material.
U.S. Pat. No. 2,683,373 discloses an apparatus for sampling grain flowing gravitationally through a pipe 34, including a slidable and rotatable cup 11 movable into and out of the stream of grain through an opening 32 in pipe wall 33. The cup 11 faces upwardly in pipe 34 to fill and while it is moved out to a position above container 35. While above the container the cup is inverted so that the collected grain sample falls into container 11.
None of the prior art disclosures teaches an apparatus for automatically sampling particulate material such as wood chips undergoing downward flow, and which characteristically vary in shape and size.
It is an objective of the present invention to provide an improved apparatus for sampling wood chips.
It is a further, more specific objective to provide a sampling probe that is solely rotational in provision of opened and closed positions, and wherein the opened position accommodates flow of the sampled downwardly flowing chips directly into a collecting container.